Disulfiram-like reaction w/ alcohol. Increase risk of cardiotoxicity (QT prolongation, Torsade de pointes, cardiac arrest) w/ amiodaron. Increases plasma conc of astemizole & terfenadine. CNS related effects (eg, psychotic reactions) w/ disulfiram. Increased blood levels of phenytoin. Decreased blood levels w/ phenobarb. Increased blood levels & toxicity of fluorouracil & lithium. Increased blood conc of carbamazepine. Increased effect of anticoagulants. Increased risk of cyclosporine toxicity. Increased blood levels & risk of neurologic side effects w/ cimetidine. Miconazole
Increased bleeding risk w/ acenocoumarol, anisindione, dicumarol, phenindione, phenprocoumon, warfarin. Increases plasma conc of astemizole, cisapride & terfenadine. Increases phenytoin toxicity risk (ataxy, hyperlexia, nystagmus, tremor). Increase or prolonged opioid effects (CNS depression, resp depression) w/ fentanyl. Increased hypoglycemic action of glimepiride. Decreased metabolism of carbamazepine. Increased plasma conc or exposure to oxybutinin. Increased plasma conc & reduction clearance of oxycodone. Increased cardiotoxicity risk (QT prolongation, torsades de pointes, cardiac arrest) w/ pimozide. Increased risk of cyclosporine toxicity (renal dysfunction, cholestasis, parasthesias). Increased bioavalaibility of tolterodine in patients deficient w/ CYP450 2D6 activity. Increased trimetrexate toxicity (bone marrow suppression, renal and hepatic dysfunction and gastrointestinal ulceration). Do not use w/ barrier contraceptives eg, condoms as may lead to breaking of rubber.